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