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