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