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