One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,4)(3,7,8,6)(9,10,15,19)(11,20,21,16)(12,17,22,24)(13,14,18,23)(25,26,30,34)(27,29,33,31)(28,36,39,32)(35,38,37,40)(1,3)(2,6)(4,7)(5,8)(11,21)(12,22)(16,20)(17,24)(25,27,30,33)(26,31,34,29)(28,37,39,35)(32,40,36,38)(9,11)(10,16)(12,18)(13,22)(14,17)(15,21)(19,20)(23,24)(25,26)(27,31)(28,32)(29,33)(30,34)(35,38)(36,39)(37,40) involution — undirected(2,4)(6,7)(9,12,15,22)(10,17,19,24)(11,18,21,13)(14,20,23,16)(25,28,30,39)(26,32,34,36)(27,35,33,37)(29,40,31,38)(1,3)(2,6)(4,7)(5,8)(9,13,15,18)(10,14,19,23)(11,22,21,12)(16,17,20,24)(1,4,5,2)(3,7,8,6)(9,14)(10,18)(11,17)(12,16)(13,19)(15,23)(20,22)(21,24)(25,29,30,31)(26,33,34,27)(28,38,39,40)(32,35,36,37)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.