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