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