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