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