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