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