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