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