One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,15,17)(11,16,20,24)(12,13,18,23)(14,22,21,19)(25,26,30,34)(27,35,37,31)(28,38,39,32)(29,33,36,40)(1,2,5,8)(3,4,7,6)(9,11,15,20)(10,16,17,24)(12,21,18,14)(13,19,23,22)(25,27,30,37)(26,31,34,35)(28,29,39,36)(32,33,38,40)(1,3)(2,6)(4,8)(5,7)(10,17)(11,20)(12,18)(19,22)(25,28,30,39)(26,32,34,38)(27,36,37,29)(31,40,35,33)(1,4)(2,7)(3,8)(5,6)(9,12)(10,13)(11,21)(14,20)(15,18)(16,19)(17,23)(22,24)(25,28)(26,32)(27,29)(30,39)(31,33)(34,38)(35,40)(36,37) involution — undirected(1,3)(2,4)(5,7)(6,8)(9,13)(10,18)(11,22)(12,17)(14,24)(15,23)(16,21)(19,20)(25,29)(26,33)(27,28)(30,36)(31,32)(34,40)(35,38)(37,39) involution — undirected(1,4)(2,7)(3,8)(5,6)(9,14,15,21)(10,19,17,22)(11,12,20,18)(13,16,23,24)(25,26)(27,31)(28,32)(29,33)(30,34)(35,37)(36,40)(38,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.