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