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