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