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