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