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